1. Field of the Invention
The present invention relates to an image forming apparatus, such as a copier, a facsimile, a printer, a multifunctional machine having a combination of these functions, etc., and a method of producing toner for electro-photograph use. In particular, the present invention relates to the image forming apparatus and the method capable of forming a toner image on a photoconductive member, and transferring the toner image onto an intermediate transfer member, and ultimately on a printing medium.
2. Discussion of the Background Art
In a conventional image formation process, in which component color toner images are formed and transferred from surfaces of respective photoconductive members serving as primary image bearers (e.g. latent image bearers) onto a printing medium, such as a plain paper, etc., via an intermediate transfer member serving as a second image bearer, so-called incomplete toner image transfer sometimes occurs. Such incomplete toner image transfer is prominent when either a character or line image is formed. This is because, in a contact type transfer system, a toner image is bore protruding from the surface of the photoconductive member and an image area rate of the character or line image is low, pressure created at a time of image transfer onto the intermediate transfer member readily concentrates on the toner, thereby degrading transfer efficiency. As a result, the incomplete toner image transfer occurs.
To suppress the incomplete toner image transfer, various ideas have been proposed as discussed in the Japanese Patent Application Laid Open Nos. 6-250414, 2001-235946, 2004-334004, 2005-10389, and 2008-003554.
However, admitting that the incomplete toner image transfer can be suppressed on a prescribed condition, another type of an abnormal image is created or physicality changes when used for a long term.
Further, as a result of various considerations and investigations, it is revealed that the incomplete toner image transfer from the photoconductive member to the intermediate transfer member is largely affected by a mutual relation between an adherence caused between toners, that caused between the toner and the intermediate transfer member, and that causes between the toner and a photoconductive member each after a completion force is applied thereto. Specifically, a non-electro static adherence between toners and that between the toner and the member increase in accordance with the completion force and a toner particle diameter. The incomplete toner image transfer becomes serious when the adherence between the toners exceeds than that caused between the toner and the intermediate transfer member, while the adherence caused between toners exceeds than that caused between the toner and the intermediate transfer member. However, none of the prior arts discusses the relation between the adherence caused between toners, that caused between the toner and the photoconductive member, and that caused between the toner and the intermediate transfer member after a prescribed compression force is applied to the electro photographic use toner.